We here report a double amplification strategy to construct a fluorescence anisotropy sensor for microRNA analysis in practical biological samples. In this strategy, one target can trigger cyclic catalyzed hairpin assembly (CHA), with streptavidin incorporated as an ampli?er of molar mass to enhance the signal intensity. The proposed strategy has a good linearity in the range of 5 pM - 0.5 nM with a detection limit down to 2.3 pM. More importantly, by using fluorescence anisotropy as the signal output, the strategy can be used directly for detection of miRNA in practical samples without any tedious sample pretreatment, holding the practical value in real biological systems.Fluorescamine is a popular fluorescent probe. We report for the first time that luminol chemiluminescence (CL) can be enhanced by fluorescamine in the presence of PVP. The CL intensity of luminol-fluorescamine-PVP is about 26 times stronger than that of luminol. Both the removal of oxygen and the addition of superoxide dismutase (SOD) decrease CL intensity, thiourea and NaN3 have little effect on CL intensities, indicating that O2?- is critical for CL. Interestingly, o-quinone generated from phenol by tyrosinase obviously inhibited the CL intensity. Inspired by such quenching effect on the luminol-fluorescamine-PVP CL system, a sensitive CL sensing for the determination of tyrosinase activity was developed. The method can detect tyrosinase in the range of 0.07-1.5 μg mL-1 (0.19-4.02 U mL-1) with the detection limit of 0.035 μg mL-1 (0.094 U mL-1). Moreover, this method exhibits satisfied recoveries for the spiked human serum samples.Because of the important advantages as rapidity, cost effectiveness and no sample preparation necessity, encountered in most of the cases, Raman spectroscopy gained more and more attention during the last years with regard to its application in food and beverages authenticity. Vegetable cold-pressed oils obtained from sesame, hemp, walnut, linseed, pumpkin and sea buckthorn have gained increased attention in consumer interest due to their high nutrient value and health benefits. The high commercial value of these, brought the temptation from some unfair producers and sellers to gain an illegal profit by replacing the raw material of these oils by cheaper ones (i.e. sunflower). Here a new approach based on the rapid processing of Raman spectra using Machine Learning algorithms, for edible oil authentication was developed and successfully tested. Through this approach, not only the adulteration detection was achieved but also an initial estimation of its magnitude.In matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), the analyte is usually distributed unevenly throughout the sample spot. The area with aggregated analyte molecules contributing abundant signal, is termed as "sweet spot", which results in poor detection reproducibility and makes it impossible to quantify analytes without internal standards. We proposed a strategy to eliminate sweet spot in MALDI-MS by using a hydrophobic ordered structure as target. https://www.selleckchem.com/products/ldc195943-imt1.html The target is fabricated by creating a hydrophobic silicon nanopillar array and subsequently decorating it uniformly with poly(methyl methacrylate) nanodots for capturing analytes. The sweet spot is eliminated by distributing analyte molecules uniformly on this target, and then result in a uniform MS image, which demonstrates an ideal reproducibility. Finally, with the target assisted MALDI-MS as biosensor was suitable to analyze practical sample such as bacitracin A in milk. Horse heart myoglobin and, angiotensin III molecules can be quantified without internal standard using α-cyano-4-hydroxycinnamic acid as matrix. This biosensor presented good linearity, high salts tolerance and high signal-to-noise ratio (up to 271.8), even the 1 mol/L salt concentration. This strategy could provide an alternative for improving the performance of MALDI-MS.Food contamination is a serious concern because of a high level of chemicals in food causes severe health issues. Safeguarding the public from the risk of adulterated foods has become a challenging mission. Chloropropanols are of importance to food safety and food security because they are common chemical food contaminants and believed to be carcinogenic to humans. In chemical sensing, chloropropanols are challenging analytes owing to the lacking diversity of functional groups and difficulty in targeting the hydroxyl group in aqueous environments. Moreover, because of their small molecular size, the compositions of chloropropanols remain challenging for achieving chromatographic determination. Herein, to simulate human smell and taste sensations, serum albumins, which are protein-based receptors, were introduced as low-selective receptors for differential sensing. Utilizing serum albumins, a fluorophore (PRODAN), and an additive (ascorbic acid), a differential-based optical biosensor array was developed to detect and differentiate chloropropanols. By integrating the sensor array with linear discriminant analysis (LDA), four chloropropanols were effectively differentiated based on their isomerism properties and the number of the hydroxyl groups, even at ultra-low concentration (5 nM). This concentration is far below the maximum tolerable level of 0.18 μM for chloropropanols. The sensing array was then employed for chloropropanols differentiation and quantification in the complex mixtures (e.g., synthetic soy and dark soy sauces). Leave-one-out cross-validation (LOOCV) analysis demonstrated 100% accurate classification for all tests. These results signify our differential sensing array as a practical and powerful tool to speedily identify, differentiate, and even quantify chloropropanols in food matrices.Graphene quantum dots and magnetite nanoparticles were embedded in molecularly imprinted polymer (GQDs@Fe3O4/MIP) to develop a magnetic nanocomposite fluorescent probe that could enrich and detect trace ceftazidime in milk in conjunction with an optosensor. Graphene quantum dots enhanced the sensitivity of the optosensor and the specificity of the molecularly imprinted polymer reinforced the selectivity of the nanocomposite probe. The incorporated magnetite nanoparticles increased enrichment of the target analyte so that a smaller volume of detecting solution could be used. The developed probe was characterized and the preparation procedure and detection conditions were optimized. In the optimum conditions, linearity was in the range of 0.10-10.0 μg L-1 and the limit of detection was 0.05 μg L-1. The developed system was utilized to detect ceftazidime in milk samples. Recoveries were in the range of 90.7-99.2% with RSD below 6% and the obtained results agreed well those obtained with chromatographic technique.